Why does my period start and then stop after a couple of hours and wont restart until the next day. ?

Endometrial breakup: The lining of the uterus is breaking down slowly and the cervical opening allows some of it to be seen vaginally early, then the next day more is "let loose". All of this is normal except for patients who have fibroids of the uterus who will have this pattern caused by the fibroid growth.(pre-menstrual staining). Have a md do an ultrasound exam to rule out fibroids.